public static (List <Node> nodes, int variableCount) Parse(string source)
{
var Nodes = new List <Node>();
var variables = new Dictionary <string, int>();
bool inExpression = false;
NodeType currentMod = NodeType.NoOperation;
Stack <Node> BlockLevel = new Stack <Node>();
using (TokenReader tr = new TokenReader(source))
{
do
{
if (string.IsNullOrWhiteSpace(tr.Current()))
{
continue;
}
if (tr.EqualTo("if"))
{
BlockLevel.Push(new Node(NodeType.JumpNotTrue));
inExpression = true;
}
else if (tr.EqualTo("while"))
{
BlockLevel.Push(new Node(NodeType.JumpNotTrue, Nodes.Count));
inExpression = true;
}
else if (tr.EqualTo("is", "smaller", "then"))
{
currentMod = NodeType.Smaller;
tr.MoveNext(2);
}
else if (tr.EqualTo("is", "larger", "then"))
{
currentMod = NodeType.Larger;
tr.MoveNext(2);
}
else if (tr.EqualTo("then") || tr.EqualTo("loop"))
{
Nodes.Add(BlockLevel.Peek());
inExpression = false;
}
else if (tr.EqualTo("end"))
{
BlockLevel.Pop().A = Nodes.Count;
Nodes.Add(new Node(NodeType.NoOperation));
}
else if (tr.EqualTo("next"))
{
var lvl = BlockLevel.Pop();
Nodes.Add(new Node(NodeType.GoTo, lvl.A));
lvl.A = Nodes.Count;
Nodes.Add(new Node(NodeType.NoOperation));
}
else if (tr.EqualTo("increment"))
{
if (tr.MoveNext() && !tr.IsNumberLiteral())
{
Nodes.Add(new Node(NodeType.Increment,
GetVarIndex(tr.Current(), variables)));
}
else
{
throw new Exception("Expected a variable after increment");
}
}
else if (tr.EqualTo("decrement"))
{
if (tr.MoveNext() && !tr.IsNumberLiteral())
{
Nodes.Add(new Node(NodeType.Decrement,
GetVarIndex(tr.Current(), variables)));
}
else
{
throw new Exception("Expected a variable after increment");
}
}
else if (tr.EqualTo("write"))
{
if (tr.MoveNext())
{
int index = -1;
decimal value = 0;
if (tr.IsNumberLiteral())
{
value = tr.GetValue();
}
else
{
index = GetVarIndex(tr.Current(), variables);
}
if (tr.MoveNext())
{
if (tr.EqualTo("to", "the", "console"))
{
if (index == -1)
{
Nodes.Add(new Node(NodeType.LoadNumLiteralWriteConsole, value));
}
else
{
Nodes.Add(new Node(NodeType.LoadLocalWriteConsole, index));
}
tr.MoveNext(2);
}
}
else
{
throw new Exception("Expected what to write to, after value!");
}
}
else
{
throw new Exception("Expected a value to write");
}
}
else if (tr.EqualTo("is", "not", "equal", "to"))
{
currentMod = NodeType.NotEqual;
tr.MoveNext(3);
}
else if (tr.EqualTo("is", "equal", "to"))
{
currentMod = NodeType.Equal;
tr.MoveNext(2);
}
else if (tr.EqualTo("a", "variable", "named"))
{
if (tr.MoveNext(3))
{
Nodes.Add(new Node(NodeType.LoadLocal,
GetVarIndex(tr.Current(), variables)));
if (currentMod != NodeType.NoOperation)
{
Nodes.Add(new Node(currentMod));
currentMod = NodeType.NoOperation;
}
}
else
{
throw new Exception("Expected name after a variable named");
}
}
else
{
if (inExpression)
{
if (tr.IsNumberLiteral())
{
Nodes.Add(new Node(NodeType.LoadNumLiteral, tr.GetValue()));
}
else
{
Nodes.Add(new Node(NodeType.LoadLocal,
GetVarIndex(tr.Current(), variables)));
}
if (currentMod != NodeType.NoOperation)
{
Nodes.Add(new Node(currentMod));
currentMod = NodeType.NoOperation;
}
}
else
{
int index = GetVarIndex(tr.Current(), variables);
if (tr.MoveNext() && tr.EqualTo("equals"))
{
tr.MoveNext();
if (tr.IsNumberLiteral())
{
Nodes.Add(new Node(NodeType.LoadNumLiteralAndStoreLocal, index, tr.GetValue()));
}
else
{
Nodes.Add(new Node(NodeType.LoadLocalAndStoreLocal, index,
GetVarIndex(tr.Current(), variables)));
}
}
else
{
throw new Exception("Expected something after the variable");
}
}
}
} while (tr.MoveNext());
}
return(Nodes, variables.Count);
}
public static void Main()
{
var Nodes = new List <Node>();
var variables = new Dictionary <string, int>();
string source =
@"
a equals 10
b equals 15
decrement b
decrement b
decrement b
decrement b
decrement b
if a variable named a is not equal to a variable named b then
a equals b
end
write a to the console
";
Console.WriteLine(source);
bool inExpression = false;
NodeType currentMod = NodeType.NoOperation;
Queue <Node> BlockLevel = new Queue <Node>();
using (TokenReader tr = new TokenReader(source))
{
do
{
if (string.IsNullOrWhiteSpace(tr.Current()))
{
continue;
}
if (tr.EqualTo("if"))
{
BlockLevel.Enqueue(new Node(NodeType.JumpNotTrue));
inExpression = true;
}
else if (tr.EqualTo("then"))
{
Nodes.Add(BlockLevel.Peek());
inExpression = false;
}
else if (tr.EqualTo("end"))
{
BlockLevel.Dequeue().A = Nodes.Count;
Nodes.Add(new Node(NodeType.NoOperation));
}
else if (tr.EqualTo("increment"))
{
if (tr.MoveNext() && !tr.IsNumberLiteral())
{
Nodes.Add(new Node(NodeType.Increment,
GetVarIndex(tr.Current(), variables)));
}
else
{
throw new Exception("Expected a variable after increment");
}
}
else if (tr.EqualTo("decrement"))
{
if (tr.MoveNext() && !tr.IsNumberLiteral())
{
Nodes.Add(new Node(NodeType.Decrement,
GetVarIndex(tr.Current(), variables)));
}
else
{
throw new Exception("Expected a variable after increment");
}
}
else if (tr.EqualTo("write"))
{
if (tr.MoveNext())
{
int index = -1;
decimal value = 0;
if (tr.IsNumberLiteral())
{
value = tr.GetValue();
}
else
{
index = GetVarIndex(tr.Current(), variables);
}
if (tr.MoveNext())
{
if (tr.EqualTo("to", "the", "console"))
{
if (index == -1)
{
Nodes.Add(new Node(NodeType.LoadNumLiteralWriteConsole, value));
}
else
{
Nodes.Add(new Node(NodeType.LoadLocalWriteConsole, index));
}
tr.MoveNext(2);
}
}
else
{
throw new Exception("Expected what to write to, after value!");
}
}
else
{
throw new Exception("Expected a value to write");
}
}
else if (tr.EqualTo("is", "not", "equal", "to"))
{
// Nodes.Add(new Node(NodeType.NotEqual));
currentMod = NodeType.NotEqual;
tr.MoveNext(3);
}
else if (tr.EqualTo("is", "equal", "to"))
{
currentMod = NodeType.Equal;
//Nodes.Add(new Node(NodeType.Equal));
tr.MoveNext(2);
}
else if (tr.EqualTo("a", "variable", "named"))
{
if (tr.MoveNext(3))
{
Nodes.Add(new Node(NodeType.LoadLocal,
GetVarIndex(tr.Current(), variables)));
if (currentMod != NodeType.NoOperation)
{
Nodes.Add(new Node(currentMod));
currentMod = NodeType.NoOperation;
}
}
else
{
throw new Exception("Expected name after a variable named");
}
}
else
{
if (inExpression)
{
if (tr.IsNumberLiteral())
{
Nodes.Add(new Node(NodeType.LoadNumLiteral, tr.GetValue()));
}
else
{
Nodes.Add(new Node(NodeType.LoadLocal,
GetVarIndex(tr.Current(), variables)));
}
if (currentMod != NodeType.NoOperation)
{
Nodes.Add(new Node(currentMod));
currentMod = NodeType.NoOperation;
}
}
else
{
int index = GetVarIndex(tr.Current(), variables);
if (tr.MoveNext() && tr.EqualTo("equals"))
{
tr.MoveNext();
if (tr.IsNumberLiteral())
{
Nodes.Add(new Node(NodeType.LoadNumLiteralAndStoreLocal, index, tr.GetValue()));
}
else
{
Nodes.Add(new Node(NodeType.LoadLocalAndStoreLocal, index,
GetVarIndex(tr.Current(), variables)));
}
}
else
{
throw new Exception("Expected something after the variable");
}
}
}
} while (tr.MoveNext());
ExecuteNodes(Nodes, variables.Count);
}
}